Agricultural irrigation systems, such as center pivot irrigation machines, are commonly used to irrigate crops. A center pivot irrigation machine typically includes, among other things, a central pivot communicating with a pressurized water supply, a series of mobile support towers connected to the central pivot and to one another by truss-type framework sections, an elevated water distribution conduit supported by the framework sections, and a number of sprinkler heads, spray guns, drop nozzles, or other fluid-emitting devices spaced along the length of the conduit. The mobile support towers are supported on wheels that are typically driven at slow speeds to move the system in a generally circular path about the central pivot to irrigate a large tract of land.
Conventionally, the wheels of the support towers are driven by a motor on each tower. Such an arrangement provides satisfactory performance, although those of ordinary skill in the art will appreciate that it is expensive to provide power to numerous multiple motors. Additionally, with a traditional central power source, such as at the central pivot, long power transmission devices, such as wires, cables, or the like, must extend out to the far reaches of the irrigation system in order to provide electrical power all the way to the motor on the tower and the end of the span. This necessary cost of transmitting electrical power is also expensive and can lead to costly repairs should the need arise or a problem be found within the power transmission lines.